projects/linux·blob v2.6.26 · refs

1792 lines · 40.5 KiB

1/*
2 * linux/fs/exec.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7/*
8 * #!-checking implemented by tytso.
9 */
10/*
11 * Demand-loading implemented 01.12.91 - no need to read anything but
12 * the header into memory. The inode of the executable is put into
13 * "current->executable", and page faults do the actual loading. Clean.
14 *
15 * Once more I can proudly say that linux stood up to being changed: it
16 * was less than 2 hours work to get demand-loading completely implemented.
17 *
18 * Demand loading changed July 1993 by Eric Youngdale. Use mmap instead,
19 * current->executable is only used by the procfs. This allows a dispatch
20 * table to check for several different types of binary formats. We keep
21 * trying until we recognize the file or we run out of supported binary
22 * formats.
23 */
24
25#include <linux/slab.h>
26#include <linux/file.h>
27#include <linux/fdtable.h>
28#include <linux/mman.h>
29#include <linux/stat.h>
30#include <linux/fcntl.h>
31#include <linux/smp_lock.h>
32#include <linux/string.h>
33#include <linux/init.h>
34#include <linux/pagemap.h>
35#include <linux/highmem.h>
36#include <linux/spinlock.h>
37#include <linux/key.h>
38#include <linux/personality.h>
39#include <linux/binfmts.h>
40#include <linux/swap.h>
41#include <linux/utsname.h>
42#include <linux/pid_namespace.h>
43#include <linux/module.h>
44#include <linux/namei.h>
45#include <linux/proc_fs.h>
46#include <linux/ptrace.h>
47#include <linux/mount.h>
48#include <linux/security.h>
49#include <linux/syscalls.h>
50#include <linux/rmap.h>
51#include <linux/tsacct_kern.h>
52#include <linux/cn_proc.h>
53#include <linux/audit.h>
54
55#include <asm/uaccess.h>
56#include <asm/mmu_context.h>
57#include <asm/tlb.h>
58
59#ifdef CONFIG_KMOD
60#include <linux/kmod.h>
61#endif
62
63#ifdef __alpha__
64/* for /sbin/loader handling in search_binary_handler() */
65#include <linux/a.out.h>
66#endif
67
68int core_uses_pid;
69char core_pattern[CORENAME_MAX_SIZE] = "core";
70int suid_dumpable = 0;
71
72/* The maximal length of core_pattern is also specified in sysctl.c */
73
74static LIST_HEAD(formats);
75static DEFINE_RWLOCK(binfmt_lock);
76
77int register_binfmt(struct linux_binfmt * fmt)
78{
79 if (!fmt)
80 return -EINVAL;
81 write_lock(&binfmt_lock);
82 list_add(&fmt->lh, &formats);
83 write_unlock(&binfmt_lock);
84 return 0;
85}
86
87EXPORT_SYMBOL(register_binfmt);
88
89void unregister_binfmt(struct linux_binfmt * fmt)
90{
91 write_lock(&binfmt_lock);
92 list_del(&fmt->lh);
93 write_unlock(&binfmt_lock);
94}
95
96EXPORT_SYMBOL(unregister_binfmt);
97
98static inline void put_binfmt(struct linux_binfmt * fmt)
99{
100 module_put(fmt->module);
101}
102
103/*
104 * Note that a shared library must be both readable and executable due to
105 * security reasons.
106 *
107 * Also note that we take the address to load from from the file itself.
108 */
109asmlinkage long sys_uselib(const char __user * library)
110{
111 struct file * file;
112 struct nameidata nd;
113 int error;
114
115 error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
116 if (error)
117 goto out;
118
119 error = -EINVAL;
120 if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
121 goto exit;
122
123 error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
124 if (error)
125 goto exit;
126
127 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
128 error = PTR_ERR(file);
129 if (IS_ERR(file))
130 goto out;
131
132 error = -ENOEXEC;
133 if(file->f_op) {
134 struct linux_binfmt * fmt;
135
136 read_lock(&binfmt_lock);
137 list_for_each_entry(fmt, &formats, lh) {
138 if (!fmt->load_shlib)
139 continue;
140 if (!try_module_get(fmt->module))
141 continue;
142 read_unlock(&binfmt_lock);
143 error = fmt->load_shlib(file);
144 read_lock(&binfmt_lock);
145 put_binfmt(fmt);
146 if (error != -ENOEXEC)
147 break;
148 }
149 read_unlock(&binfmt_lock);
150 }
151 fput(file);
152out:
153 return error;
154exit:
155 release_open_intent(&nd);
156 path_put(&nd.path);
157 goto out;
158}
159
160#ifdef CONFIG_MMU
161
162static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
163 int write)
164{
165 struct page *page;
166 int ret;
167
168#ifdef CONFIG_STACK_GROWSUP
169 if (write) {
170 ret = expand_stack_downwards(bprm->vma, pos);
171 if (ret < 0)
172 return NULL;
173 }
174#endif
175 ret = get_user_pages(current, bprm->mm, pos,
176 1, write, 1, &page, NULL);
177 if (ret <= 0)
178 return NULL;
179
180 if (write) {
181 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
182 struct rlimit *rlim;
183
184 /*
185 * We've historically supported up to 32 pages (ARG_MAX)
186 * of argument strings even with small stacks
187 */
188 if (size <= ARG_MAX)
189 return page;
190
191 /*
192 * Limit to 1/4-th the stack size for the argv+env strings.
193 * This ensures that:
194 * - the remaining binfmt code will not run out of stack space,
195 * - the program will have a reasonable amount of stack left
196 * to work from.
197 */
198 rlim = current->signal->rlim;
199 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
200 put_page(page);
201 return NULL;
202 }
203 }
204
205 return page;
206}
207
208static void put_arg_page(struct page *page)
209{
210 put_page(page);
211}
212
213static void free_arg_page(struct linux_binprm *bprm, int i)
214{
215}
216
217static void free_arg_pages(struct linux_binprm *bprm)
218{
219}
220
221static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
222 struct page *page)
223{
224 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
225}
226
227static int __bprm_mm_init(struct linux_binprm *bprm)
228{
229 int err = -ENOMEM;
230 struct vm_area_struct *vma = NULL;
231 struct mm_struct *mm = bprm->mm;
232
233 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
234 if (!vma)
235 goto err;
236
237 down_write(&mm->mmap_sem);
238 vma->vm_mm = mm;
239
240 /*
241 * Place the stack at the largest stack address the architecture
242 * supports. Later, we'll move this to an appropriate place. We don't
243 * use STACK_TOP because that can depend on attributes which aren't
244 * configured yet.
245 */
246 vma->vm_end = STACK_TOP_MAX;
247 vma->vm_start = vma->vm_end - PAGE_SIZE;
248
249 vma->vm_flags = VM_STACK_FLAGS;
250 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
251 err = insert_vm_struct(mm, vma);
252 if (err) {
253 up_write(&mm->mmap_sem);
254 goto err;
255 }
256
257 mm->stack_vm = mm->total_vm = 1;
258 up_write(&mm->mmap_sem);
259
260 bprm->p = vma->vm_end - sizeof(void *);
261
262 return 0;
263
264err:
265 if (vma) {
266 bprm->vma = NULL;
267 kmem_cache_free(vm_area_cachep, vma);
268 }
269
270 return err;
271}
272
273static bool valid_arg_len(struct linux_binprm *bprm, long len)
274{
275 return len <= MAX_ARG_STRLEN;
276}
277
278#else
279
280static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
281 int write)
282{
283 struct page *page;
284
285 page = bprm->page[pos / PAGE_SIZE];
286 if (!page && write) {
287 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
288 if (!page)
289 return NULL;
290 bprm->page[pos / PAGE_SIZE] = page;
291 }
292
293 return page;
294}
295
296static void put_arg_page(struct page *page)
297{
298}
299
300static void free_arg_page(struct linux_binprm *bprm, int i)
301{
302 if (bprm->page[i]) {
303 __free_page(bprm->page[i]);
304 bprm->page[i] = NULL;
305 }
306}
307
308static void free_arg_pages(struct linux_binprm *bprm)
309{
310 int i;
311
312 for (i = 0; i < MAX_ARG_PAGES; i++)
313 free_arg_page(bprm, i);
314}
315
316static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
317 struct page *page)
318{
319}
320
321static int __bprm_mm_init(struct linux_binprm *bprm)
322{
323 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
324 return 0;
325}
326
327static bool valid_arg_len(struct linux_binprm *bprm, long len)
328{
329 return len <= bprm->p;
330}
331
332#endif /* CONFIG_MMU */
333
334/*
335 * Create a new mm_struct and populate it with a temporary stack
336 * vm_area_struct. We don't have enough context at this point to set the stack
337 * flags, permissions, and offset, so we use temporary values. We'll update
338 * them later in setup_arg_pages().
339 */
340int bprm_mm_init(struct linux_binprm *bprm)
341{
342 int err;
343 struct mm_struct *mm = NULL;
344
345 bprm->mm = mm = mm_alloc();
346 err = -ENOMEM;
347 if (!mm)
348 goto err;
349
350 err = init_new_context(current, mm);
351 if (err)
352 goto err;
353
354 err = __bprm_mm_init(bprm);
355 if (err)
356 goto err;
357
358 return 0;
359
360err:
361 if (mm) {
362 bprm->mm = NULL;
363 mmdrop(mm);
364 }
365
366 return err;
367}
368
369/*
370 * count() counts the number of strings in array ARGV.
371 */
372static int count(char __user * __user * argv, int max)
373{
374 int i = 0;
375
376 if (argv != NULL) {
377 for (;;) {
378 char __user * p;
379
380 if (get_user(p, argv))
381 return -EFAULT;
382 if (!p)
383 break;
384 argv++;
385 if(++i > max)
386 return -E2BIG;
387 cond_resched();
388 }
389 }
390 return i;
391}
392
393/*
394 * 'copy_strings()' copies argument/environment strings from the old
395 * processes's memory to the new process's stack. The call to get_user_pages()
396 * ensures the destination page is created and not swapped out.
397 */
398static int copy_strings(int argc, char __user * __user * argv,
399 struct linux_binprm *bprm)
400{
401 struct page *kmapped_page = NULL;
402 char *kaddr = NULL;
403 unsigned long kpos = 0;
404 int ret;
405
406 while (argc-- > 0) {
407 char __user *str;
408 int len;
409 unsigned long pos;
410
411 if (get_user(str, argv+argc) ||
412 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
413 ret = -EFAULT;
414 goto out;
415 }
416
417 if (!valid_arg_len(bprm, len)) {
418 ret = -E2BIG;
419 goto out;
420 }
421
422 /* We're going to work our way backwords. */
423 pos = bprm->p;
424 str += len;
425 bprm->p -= len;
426
427 while (len > 0) {
428 int offset, bytes_to_copy;
429
430 offset = pos % PAGE_SIZE;
431 if (offset == 0)
432 offset = PAGE_SIZE;
433
434 bytes_to_copy = offset;
435 if (bytes_to_copy > len)
436 bytes_to_copy = len;
437
438 offset -= bytes_to_copy;
439 pos -= bytes_to_copy;
440 str -= bytes_to_copy;
441 len -= bytes_to_copy;
442
443 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
444 struct page *page;
445
446 page = get_arg_page(bprm, pos, 1);
447 if (!page) {
448 ret = -E2BIG;
449 goto out;
450 }
451
452 if (kmapped_page) {
453 flush_kernel_dcache_page(kmapped_page);
454 kunmap(kmapped_page);
455 put_arg_page(kmapped_page);
456 }
457 kmapped_page = page;
458 kaddr = kmap(kmapped_page);
459 kpos = pos & PAGE_MASK;
460 flush_arg_page(bprm, kpos, kmapped_page);
461 }
462 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
463 ret = -EFAULT;
464 goto out;
465 }
466 }
467 }
468 ret = 0;
469out:
470 if (kmapped_page) {
471 flush_kernel_dcache_page(kmapped_page);
472 kunmap(kmapped_page);
473 put_arg_page(kmapped_page);
474 }
475 return ret;
476}
477
478/*
479 * Like copy_strings, but get argv and its values from kernel memory.
480 */
481int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
482{
483 int r;
484 mm_segment_t oldfs = get_fs();
485 set_fs(KERNEL_DS);
486 r = copy_strings(argc, (char __user * __user *)argv, bprm);
487 set_fs(oldfs);
488 return r;
489}
490EXPORT_SYMBOL(copy_strings_kernel);
491
492#ifdef CONFIG_MMU
493
494/*
495 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
496 * the binfmt code determines where the new stack should reside, we shift it to
497 * its final location. The process proceeds as follows:
498 *
499 * 1) Use shift to calculate the new vma endpoints.
500 * 2) Extend vma to cover both the old and new ranges. This ensures the
501 * arguments passed to subsequent functions are consistent.
502 * 3) Move vma's page tables to the new range.
503 * 4) Free up any cleared pgd range.
504 * 5) Shrink the vma to cover only the new range.
505 */
506static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
507{
508 struct mm_struct *mm = vma->vm_mm;
509 unsigned long old_start = vma->vm_start;
510 unsigned long old_end = vma->vm_end;
511 unsigned long length = old_end - old_start;
512 unsigned long new_start = old_start - shift;
513 unsigned long new_end = old_end - shift;
514 struct mmu_gather *tlb;
515
516 BUG_ON(new_start > new_end);
517
518 /*
519 * ensure there are no vmas between where we want to go
520 * and where we are
521 */
522 if (vma != find_vma(mm, new_start))
523 return -EFAULT;
524
525 /*
526 * cover the whole range: [new_start, old_end)
527 */
528 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
529
530 /*
531 * move the page tables downwards, on failure we rely on
532 * process cleanup to remove whatever mess we made.
533 */
534 if (length != move_page_tables(vma, old_start,
535 vma, new_start, length))
536 return -ENOMEM;
537
538 lru_add_drain();
539 tlb = tlb_gather_mmu(mm, 0);
540 if (new_end > old_start) {
541 /*
542 * when the old and new regions overlap clear from new_end.
543 */
544 free_pgd_range(&tlb, new_end, old_end, new_end,
545 vma->vm_next ? vma->vm_next->vm_start : 0);
546 } else {
547 /*
548 * otherwise, clean from old_start; this is done to not touch
549 * the address space in [new_end, old_start) some architectures
550 * have constraints on va-space that make this illegal (IA64) -
551 * for the others its just a little faster.
552 */
553 free_pgd_range(&tlb, old_start, old_end, new_end,
554 vma->vm_next ? vma->vm_next->vm_start : 0);
555 }
556 tlb_finish_mmu(tlb, new_end, old_end);
557
558 /*
559 * shrink the vma to just the new range.
560 */
561 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
562
563 return 0;
564}
565
566#define EXTRA_STACK_VM_PAGES 20 /* random */
567
568/*
569 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
570 * the stack is optionally relocated, and some extra space is added.
571 */
572int setup_arg_pages(struct linux_binprm *bprm,
573 unsigned long stack_top,
574 int executable_stack)
575{
576 unsigned long ret;
577 unsigned long stack_shift;
578 struct mm_struct *mm = current->mm;
579 struct vm_area_struct *vma = bprm->vma;
580 struct vm_area_struct *prev = NULL;
581 unsigned long vm_flags;
582 unsigned long stack_base;
583
584#ifdef CONFIG_STACK_GROWSUP
585 /* Limit stack size to 1GB */
586 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
587 if (stack_base > (1 << 30))
588 stack_base = 1 << 30;
589
590 /* Make sure we didn't let the argument array grow too large. */
591 if (vma->vm_end - vma->vm_start > stack_base)
592 return -ENOMEM;
593
594 stack_base = PAGE_ALIGN(stack_top - stack_base);
595
596 stack_shift = vma->vm_start - stack_base;
597 mm->arg_start = bprm->p - stack_shift;
598 bprm->p = vma->vm_end - stack_shift;
599#else
600 stack_top = arch_align_stack(stack_top);
601 stack_top = PAGE_ALIGN(stack_top);
602 stack_shift = vma->vm_end - stack_top;
603
604 bprm->p -= stack_shift;
605 mm->arg_start = bprm->p;
606#endif
607
608 if (bprm->loader)
609 bprm->loader -= stack_shift;
610 bprm->exec -= stack_shift;
611
612 down_write(&mm->mmap_sem);
613 vm_flags = VM_STACK_FLAGS;
614
615 /*
616 * Adjust stack execute permissions; explicitly enable for
617 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
618 * (arch default) otherwise.
619 */
620 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
621 vm_flags |= VM_EXEC;
622 else if (executable_stack == EXSTACK_DISABLE_X)
623 vm_flags &= ~VM_EXEC;
624 vm_flags |= mm->def_flags;
625
626 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
627 vm_flags);
628 if (ret)
629 goto out_unlock;
630 BUG_ON(prev != vma);
631
632 /* Move stack pages down in memory. */
633 if (stack_shift) {
634 ret = shift_arg_pages(vma, stack_shift);
635 if (ret) {
636 up_write(&mm->mmap_sem);
637 return ret;
638 }
639 }
640
641#ifdef CONFIG_STACK_GROWSUP
642 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
643#else
644 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
645#endif
646 ret = expand_stack(vma, stack_base);
647 if (ret)
648 ret = -EFAULT;
649
650out_unlock:
651 up_write(&mm->mmap_sem);
652 return 0;
653}
654EXPORT_SYMBOL(setup_arg_pages);
655
656#endif /* CONFIG_MMU */
657
658struct file *open_exec(const char *name)
659{
660 struct nameidata nd;
661 int err;
662 struct file *file;
663
664 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
665 file = ERR_PTR(err);
666
667 if (!err) {
668 struct inode *inode = nd.path.dentry->d_inode;
669 file = ERR_PTR(-EACCES);
670 if (S_ISREG(inode->i_mode)) {
671 int err = vfs_permission(&nd, MAY_EXEC);
672 file = ERR_PTR(err);
673 if (!err) {
674 file = nameidata_to_filp(&nd,
675 O_RDONLY|O_LARGEFILE);
676 if (!IS_ERR(file)) {
677 err = deny_write_access(file);
678 if (err) {
679 fput(file);
680 file = ERR_PTR(err);
681 }
682 }
683out:
684 return file;
685 }
686 }
687 release_open_intent(&nd);
688 path_put(&nd.path);
689 }
690 goto out;
691}
692
693EXPORT_SYMBOL(open_exec);
694
695int kernel_read(struct file *file, unsigned long offset,
696 char *addr, unsigned long count)
697{
698 mm_segment_t old_fs;
699 loff_t pos = offset;
700 int result;
701
702 old_fs = get_fs();
703 set_fs(get_ds());
704 /* The cast to a user pointer is valid due to the set_fs() */
705 result = vfs_read(file, (void __user *)addr, count, &pos);
706 set_fs(old_fs);
707 return result;
708}
709
710EXPORT_SYMBOL(kernel_read);
711
712static int exec_mmap(struct mm_struct *mm)
713{
714 struct task_struct *tsk;
715 struct mm_struct * old_mm, *active_mm;
716
717 /* Notify parent that we're no longer interested in the old VM */
718 tsk = current;
719 old_mm = current->mm;
720 mm_release(tsk, old_mm);
721
722 if (old_mm) {
723 /*
724 * Make sure that if there is a core dump in progress
725 * for the old mm, we get out and die instead of going
726 * through with the exec. We must hold mmap_sem around
727 * checking core_waiters and changing tsk->mm. The
728 * core-inducing thread will increment core_waiters for
729 * each thread whose ->mm == old_mm.
730 */
731 down_read(&old_mm->mmap_sem);
732 if (unlikely(old_mm->core_waiters)) {
733 up_read(&old_mm->mmap_sem);
734 return -EINTR;
735 }
736 }
737 task_lock(tsk);
738 active_mm = tsk->active_mm;
739 tsk->mm = mm;
740 tsk->active_mm = mm;
741 activate_mm(active_mm, mm);
742 task_unlock(tsk);
743 mm_update_next_owner(old_mm);
744 arch_pick_mmap_layout(mm);
745 if (old_mm) {
746 up_read(&old_mm->mmap_sem);
747 BUG_ON(active_mm != old_mm);
748 mmput(old_mm);
749 return 0;
750 }
751 mmdrop(active_mm);
752 return 0;
753}
754
755/*
756 * This function makes sure the current process has its own signal table,
757 * so that flush_signal_handlers can later reset the handlers without
758 * disturbing other processes. (Other processes might share the signal
759 * table via the CLONE_SIGHAND option to clone().)
760 */
761static int de_thread(struct task_struct *tsk)
762{
763 struct signal_struct *sig = tsk->signal;
764 struct sighand_struct *oldsighand = tsk->sighand;
765 spinlock_t *lock = &oldsighand->siglock;
766 struct task_struct *leader = NULL;
767 int count;
768
769 if (thread_group_empty(tsk))
770 goto no_thread_group;
771
772 /*
773 * Kill all other threads in the thread group.
774 */
775 spin_lock_irq(lock);
776 if (signal_group_exit(sig)) {
777 /*
778 * Another group action in progress, just
779 * return so that the signal is processed.
780 */
781 spin_unlock_irq(lock);
782 return -EAGAIN;
783 }
784 sig->group_exit_task = tsk;
785 zap_other_threads(tsk);
786
787 /* Account for the thread group leader hanging around: */
788 count = thread_group_leader(tsk) ? 1 : 2;
789 sig->notify_count = count;
790 while (atomic_read(&sig->count) > count) {
791 __set_current_state(TASK_UNINTERRUPTIBLE);
792 spin_unlock_irq(lock);
793 schedule();
794 spin_lock_irq(lock);
795 }
796 spin_unlock_irq(lock);
797
798 /*
799 * At this point all other threads have exited, all we have to
800 * do is to wait for the thread group leader to become inactive,
801 * and to assume its PID:
802 */
803 if (!thread_group_leader(tsk)) {
804 leader = tsk->group_leader;
805
806 sig->notify_count = -1; /* for exit_notify() */
807 for (;;) {
808 write_lock_irq(&tasklist_lock);
809 if (likely(leader->exit_state))
810 break;
811 __set_current_state(TASK_UNINTERRUPTIBLE);
812 write_unlock_irq(&tasklist_lock);
813 schedule();
814 }
815
816 if (unlikely(task_child_reaper(tsk) == leader))
817 task_active_pid_ns(tsk)->child_reaper = tsk;
818 /*
819 * The only record we have of the real-time age of a
820 * process, regardless of execs it's done, is start_time.
821 * All the past CPU time is accumulated in signal_struct
822 * from sister threads now dead. But in this non-leader
823 * exec, nothing survives from the original leader thread,
824 * whose birth marks the true age of this process now.
825 * When we take on its identity by switching to its PID, we
826 * also take its birthdate (always earlier than our own).
827 */
828 tsk->start_time = leader->start_time;
829
830 BUG_ON(!same_thread_group(leader, tsk));
831 BUG_ON(has_group_leader_pid(tsk));
832 /*
833 * An exec() starts a new thread group with the
834 * TGID of the previous thread group. Rehash the
835 * two threads with a switched PID, and release
836 * the former thread group leader:
837 */
838
839 /* Become a process group leader with the old leader's pid.
840 * The old leader becomes a thread of the this thread group.
841 * Note: The old leader also uses this pid until release_task
842 * is called. Odd but simple and correct.
843 */
844 detach_pid(tsk, PIDTYPE_PID);
845 tsk->pid = leader->pid;
846 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
847 transfer_pid(leader, tsk, PIDTYPE_PGID);
848 transfer_pid(leader, tsk, PIDTYPE_SID);
849 list_replace_rcu(&leader->tasks, &tsk->tasks);
850
851 tsk->group_leader = tsk;
852 leader->group_leader = tsk;
853
854 tsk->exit_signal = SIGCHLD;
855
856 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
857 leader->exit_state = EXIT_DEAD;
858
859 write_unlock_irq(&tasklist_lock);
860 }
861
862 sig->group_exit_task = NULL;
863 sig->notify_count = 0;
864
865no_thread_group:
866 exit_itimers(sig);
867 flush_itimer_signals();
868 if (leader)
869 release_task(leader);
870
871 if (atomic_read(&oldsighand->count) != 1) {
872 struct sighand_struct *newsighand;
873 /*
874 * This ->sighand is shared with the CLONE_SIGHAND
875 * but not CLONE_THREAD task, switch to the new one.
876 */
877 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
878 if (!newsighand)
879 return -ENOMEM;
880
881 atomic_set(&newsighand->count, 1);
882 memcpy(newsighand->action, oldsighand->action,
883 sizeof(newsighand->action));
884
885 write_lock_irq(&tasklist_lock);
886 spin_lock(&oldsighand->siglock);
887 rcu_assign_pointer(tsk->sighand, newsighand);
888 spin_unlock(&oldsighand->siglock);
889 write_unlock_irq(&tasklist_lock);
890
891 __cleanup_sighand(oldsighand);
892 }
893
894 BUG_ON(!thread_group_leader(tsk));
895 return 0;
896}
897
898/*
899 * These functions flushes out all traces of the currently running executable
900 * so that a new one can be started
901 */
902static void flush_old_files(struct files_struct * files)
903{
904 long j = -1;
905 struct fdtable *fdt;
906
907 spin_lock(&files->file_lock);
908 for (;;) {
909 unsigned long set, i;
910
911 j++;
912 i = j * __NFDBITS;
913 fdt = files_fdtable(files);
914 if (i >= fdt->max_fds)
915 break;
916 set = fdt->close_on_exec->fds_bits[j];
917 if (!set)
918 continue;
919 fdt->close_on_exec->fds_bits[j] = 0;
920 spin_unlock(&files->file_lock);
921 for ( ; set ; i++,set >>= 1) {
922 if (set & 1) {
923 sys_close(i);
924 }
925 }
926 spin_lock(&files->file_lock);
927
928 }
929 spin_unlock(&files->file_lock);
930}
931
932char *get_task_comm(char *buf, struct task_struct *tsk)
933{
934 /* buf must be at least sizeof(tsk->comm) in size */
935 task_lock(tsk);
936 strncpy(buf, tsk->comm, sizeof(tsk->comm));
937 task_unlock(tsk);
938 return buf;
939}
940
941void set_task_comm(struct task_struct *tsk, char *buf)
942{
943 task_lock(tsk);
944 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
945 task_unlock(tsk);
946}
947
948int flush_old_exec(struct linux_binprm * bprm)
949{
950 char * name;
951 int i, ch, retval;
952 char tcomm[sizeof(current->comm)];
953
954 /*
955 * Make sure we have a private signal table and that
956 * we are unassociated from the previous thread group.
957 */
958 retval = de_thread(current);
959 if (retval)
960 goto out;
961
962 set_mm_exe_file(bprm->mm, bprm->file);
963
964 /*
965 * Release all of the old mmap stuff
966 */
967 retval = exec_mmap(bprm->mm);
968 if (retval)
969 goto out;
970
971 bprm->mm = NULL; /* We're using it now */
972
973 /* This is the point of no return */
974 current->sas_ss_sp = current->sas_ss_size = 0;
975
976 if (current->euid == current->uid && current->egid == current->gid)
977 set_dumpable(current->mm, 1);
978 else
979 set_dumpable(current->mm, suid_dumpable);
980
981 name = bprm->filename;
982
983 /* Copies the binary name from after last slash */
984 for (i=0; (ch = *(name++)) != '\0';) {
985 if (ch == '/')
986 i = 0; /* overwrite what we wrote */
987 else
988 if (i < (sizeof(tcomm) - 1))
989 tcomm[i++] = ch;
990 }
991 tcomm[i] = '\0';
992 set_task_comm(current, tcomm);
993
994 current->flags &= ~PF_RANDOMIZE;
995 flush_thread();
996
997 /* Set the new mm task size. We have to do that late because it may
998 * depend on TIF_32BIT which is only updated in flush_thread() on
999 * some architectures like powerpc
1000 */
1001 current->mm->task_size = TASK_SIZE;
1002
1003 if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1004 suid_keys(current);
1005 set_dumpable(current->mm, suid_dumpable);
1006 current->pdeath_signal = 0;
1007 } else if (file_permission(bprm->file, MAY_READ) ||
1008 (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1009 suid_keys(current);
1010 set_dumpable(current->mm, suid_dumpable);
1011 }
1012
1013 /* An exec changes our domain. We are no longer part of the thread
1014 group */
1015
1016 current->self_exec_id++;
1017
1018 flush_signal_handlers(current, 0);
1019 flush_old_files(current->files);
1020
1021 return 0;
1022
1023out:
1024 return retval;
1025}
1026
1027EXPORT_SYMBOL(flush_old_exec);
1028
1029/*
1030 * Fill the binprm structure from the inode.
1031 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1032 */
1033int prepare_binprm(struct linux_binprm *bprm)
1034{
1035 int mode;
1036 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1037 int retval;
1038
1039 mode = inode->i_mode;
1040 if (bprm->file->f_op == NULL)
1041 return -EACCES;
1042
1043 bprm->e_uid = current->euid;
1044 bprm->e_gid = current->egid;
1045
1046 if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1047 /* Set-uid? */
1048 if (mode & S_ISUID) {
1049 current->personality &= ~PER_CLEAR_ON_SETID;
1050 bprm->e_uid = inode->i_uid;
1051 }
1052
1053 /* Set-gid? */
1054 /*
1055 * If setgid is set but no group execute bit then this
1056 * is a candidate for mandatory locking, not a setgid
1057 * executable.
1058 */
1059 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1060 current->personality &= ~PER_CLEAR_ON_SETID;
1061 bprm->e_gid = inode->i_gid;
1062 }
1063 }
1064
1065 /* fill in binprm security blob */
1066 retval = security_bprm_set(bprm);
1067 if (retval)
1068 return retval;
1069
1070 memset(bprm->buf,0,BINPRM_BUF_SIZE);
1071 return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1072}
1073
1074EXPORT_SYMBOL(prepare_binprm);
1075
1076static int unsafe_exec(struct task_struct *p)
1077{
1078 int unsafe = 0;
1079 if (p->ptrace & PT_PTRACED) {
1080 if (p->ptrace & PT_PTRACE_CAP)
1081 unsafe |= LSM_UNSAFE_PTRACE_CAP;
1082 else
1083 unsafe |= LSM_UNSAFE_PTRACE;
1084 }
1085 if (atomic_read(&p->fs->count) > 1 ||
1086 atomic_read(&p->files->count) > 1 ||
1087 atomic_read(&p->sighand->count) > 1)
1088 unsafe |= LSM_UNSAFE_SHARE;
1089
1090 return unsafe;
1091}
1092
1093void compute_creds(struct linux_binprm *bprm)
1094{
1095 int unsafe;
1096
1097 if (bprm->e_uid != current->uid) {
1098 suid_keys(current);
1099 current->pdeath_signal = 0;
1100 }
1101 exec_keys(current);
1102
1103 task_lock(current);
1104 unsafe = unsafe_exec(current);
1105 security_bprm_apply_creds(bprm, unsafe);
1106 task_unlock(current);
1107 security_bprm_post_apply_creds(bprm);
1108}
1109EXPORT_SYMBOL(compute_creds);
1110
1111/*
1112 * Arguments are '\0' separated strings found at the location bprm->p
1113 * points to; chop off the first by relocating brpm->p to right after
1114 * the first '\0' encountered.
1115 */
1116int remove_arg_zero(struct linux_binprm *bprm)
1117{
1118 int ret = 0;
1119 unsigned long offset;
1120 char *kaddr;
1121 struct page *page;
1122
1123 if (!bprm->argc)
1124 return 0;
1125
1126 do {
1127 offset = bprm->p & ~PAGE_MASK;
1128 page = get_arg_page(bprm, bprm->p, 0);
1129 if (!page) {
1130 ret = -EFAULT;
1131 goto out;
1132 }
1133 kaddr = kmap_atomic(page, KM_USER0);
1134
1135 for (; offset < PAGE_SIZE && kaddr[offset];
1136 offset++, bprm->p++)
1137 ;
1138
1139 kunmap_atomic(kaddr, KM_USER0);
1140 put_arg_page(page);
1141
1142 if (offset == PAGE_SIZE)
1143 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1144 } while (offset == PAGE_SIZE);
1145
1146 bprm->p++;
1147 bprm->argc--;
1148 ret = 0;
1149
1150out:
1151 return ret;
1152}
1153EXPORT_SYMBOL(remove_arg_zero);
1154
1155/*
1156 * cycle the list of binary formats handler, until one recognizes the image
1157 */
1158int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1159{
1160 int try,retval;
1161 struct linux_binfmt *fmt;
1162#ifdef __alpha__
1163 /* handle /sbin/loader.. */
1164 {
1165 struct exec * eh = (struct exec *) bprm->buf;
1166
1167 if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1168 (eh->fh.f_flags & 0x3000) == 0x3000)
1169 {
1170 struct file * file;
1171 unsigned long loader;
1172
1173 allow_write_access(bprm->file);
1174 fput(bprm->file);
1175 bprm->file = NULL;
1176
1177 loader = bprm->vma->vm_end - sizeof(void *);
1178
1179 file = open_exec("/sbin/loader");
1180 retval = PTR_ERR(file);
1181 if (IS_ERR(file))
1182 return retval;
1183
1184 /* Remember if the application is TASO. */
1185 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1186
1187 bprm->file = file;
1188 bprm->loader = loader;
1189 retval = prepare_binprm(bprm);
1190 if (retval<0)
1191 return retval;
1192 /* should call search_binary_handler recursively here,
1193 but it does not matter */
1194 }
1195 }
1196#endif
1197 retval = security_bprm_check(bprm);
1198 if (retval)
1199 return retval;
1200
1201 /* kernel module loader fixup */
1202 /* so we don't try to load run modprobe in kernel space. */
1203 set_fs(USER_DS);
1204
1205 retval = audit_bprm(bprm);
1206 if (retval)
1207 return retval;
1208
1209 retval = -ENOENT;
1210 for (try=0; try<2; try++) {
1211 read_lock(&binfmt_lock);
1212 list_for_each_entry(fmt, &formats, lh) {
1213 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1214 if (!fn)
1215 continue;
1216 if (!try_module_get(fmt->module))
1217 continue;
1218 read_unlock(&binfmt_lock);
1219 retval = fn(bprm, regs);
1220 if (retval >= 0) {
1221 put_binfmt(fmt);
1222 allow_write_access(bprm->file);
1223 if (bprm->file)
1224 fput(bprm->file);
1225 bprm->file = NULL;
1226 current->did_exec = 1;
1227 proc_exec_connector(current);
1228 return retval;
1229 }
1230 read_lock(&binfmt_lock);
1231 put_binfmt(fmt);
1232 if (retval != -ENOEXEC || bprm->mm == NULL)
1233 break;
1234 if (!bprm->file) {
1235 read_unlock(&binfmt_lock);
1236 return retval;
1237 }
1238 }
1239 read_unlock(&binfmt_lock);
1240 if (retval != -ENOEXEC || bprm->mm == NULL) {
1241 break;
1242#ifdef CONFIG_KMOD
1243 }else{
1244#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1245 if (printable(bprm->buf[0]) &&
1246 printable(bprm->buf[1]) &&
1247 printable(bprm->buf[2]) &&
1248 printable(bprm->buf[3]))
1249 break; /* -ENOEXEC */
1250 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1251#endif
1252 }
1253 }
1254 return retval;
1255}
1256
1257EXPORT_SYMBOL(search_binary_handler);
1258
1259void free_bprm(struct linux_binprm *bprm)
1260{
1261 free_arg_pages(bprm);
1262 kfree(bprm);
1263}
1264
1265/*
1266 * sys_execve() executes a new program.
1267 */
1268int do_execve(char * filename,
1269 char __user *__user *argv,
1270 char __user *__user *envp,
1271 struct pt_regs * regs)
1272{
1273 struct linux_binprm *bprm;
1274 struct file *file;
1275 struct files_struct *displaced;
1276 int retval;
1277
1278 retval = unshare_files(&displaced);
1279 if (retval)
1280 goto out_ret;
1281
1282 retval = -ENOMEM;
1283 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1284 if (!bprm)
1285 goto out_files;
1286
1287 file = open_exec(filename);
1288 retval = PTR_ERR(file);
1289 if (IS_ERR(file))
1290 goto out_kfree;
1291
1292 sched_exec();
1293
1294 bprm->file = file;
1295 bprm->filename = filename;
1296 bprm->interp = filename;
1297
1298 retval = bprm_mm_init(bprm);
1299 if (retval)
1300 goto out_file;
1301
1302 bprm->argc = count(argv, MAX_ARG_STRINGS);
1303 if ((retval = bprm->argc) < 0)
1304 goto out_mm;
1305
1306 bprm->envc = count(envp, MAX_ARG_STRINGS);
1307 if ((retval = bprm->envc) < 0)
1308 goto out_mm;
1309
1310 retval = security_bprm_alloc(bprm);
1311 if (retval)
1312 goto out;
1313
1314 retval = prepare_binprm(bprm);
1315 if (retval < 0)
1316 goto out;
1317
1318 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1319 if (retval < 0)
1320 goto out;
1321
1322 bprm->exec = bprm->p;
1323 retval = copy_strings(bprm->envc, envp, bprm);
1324 if (retval < 0)
1325 goto out;
1326
1327 retval = copy_strings(bprm->argc, argv, bprm);
1328 if (retval < 0)
1329 goto out;
1330
1331 retval = search_binary_handler(bprm,regs);
1332 if (retval >= 0) {
1333 /* execve success */
1334 security_bprm_free(bprm);
1335 acct_update_integrals(current);
1336 free_bprm(bprm);
1337 if (displaced)
1338 put_files_struct(displaced);
1339 return retval;
1340 }
1341
1342out:
1343 if (bprm->security)
1344 security_bprm_free(bprm);
1345
1346out_mm:
1347 if (bprm->mm)
1348 mmput (bprm->mm);
1349
1350out_file:
1351 if (bprm->file) {
1352 allow_write_access(bprm->file);
1353 fput(bprm->file);
1354 }
1355out_kfree:
1356 free_bprm(bprm);
1357
1358out_files:
1359 if (displaced)
1360 reset_files_struct(displaced);
1361out_ret:
1362 return retval;
1363}
1364
1365int set_binfmt(struct linux_binfmt *new)
1366{
1367 struct linux_binfmt *old = current->binfmt;
1368
1369 if (new) {
1370 if (!try_module_get(new->module))
1371 return -1;
1372 }
1373 current->binfmt = new;
1374 if (old)
1375 module_put(old->module);
1376 return 0;
1377}
1378
1379EXPORT_SYMBOL(set_binfmt);
1380
1381/* format_corename will inspect the pattern parameter, and output a
1382 * name into corename, which must have space for at least
1383 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1384 */
1385static int format_corename(char *corename, const char *pattern, long signr)
1386{
1387 const char *pat_ptr = pattern;
1388 char *out_ptr = corename;
1389 char *const out_end = corename + CORENAME_MAX_SIZE;
1390 int rc;
1391 int pid_in_pattern = 0;
1392 int ispipe = 0;
1393
1394 if (*pattern == '|')
1395 ispipe = 1;
1396
1397 /* Repeat as long as we have more pattern to process and more output
1398 space */
1399 while (*pat_ptr) {
1400 if (*pat_ptr != '%') {
1401 if (out_ptr == out_end)
1402 goto out;
1403 *out_ptr++ = *pat_ptr++;
1404 } else {
1405 switch (*++pat_ptr) {
1406 case 0:
1407 goto out;
1408 /* Double percent, output one percent */
1409 case '%':
1410 if (out_ptr == out_end)
1411 goto out;
1412 *out_ptr++ = '%';
1413 break;
1414 /* pid */
1415 case 'p':
1416 pid_in_pattern = 1;
1417 rc = snprintf(out_ptr, out_end - out_ptr,
1418 "%d", task_tgid_vnr(current));
1419 if (rc > out_end - out_ptr)
1420 goto out;
1421 out_ptr += rc;
1422 break;
1423 /* uid */
1424 case 'u':
1425 rc = snprintf(out_ptr, out_end - out_ptr,
1426 "%d", current->uid);
1427 if (rc > out_end - out_ptr)
1428 goto out;
1429 out_ptr += rc;
1430 break;
1431 /* gid */
1432 case 'g':
1433 rc = snprintf(out_ptr, out_end - out_ptr,
1434 "%d", current->gid);
1435 if (rc > out_end - out_ptr)
1436 goto out;
1437 out_ptr += rc;
1438 break;
1439 /* signal that caused the coredump */
1440 case 's':
1441 rc = snprintf(out_ptr, out_end - out_ptr,
1442 "%ld", signr);
1443 if (rc > out_end - out_ptr)
1444 goto out;
1445 out_ptr += rc;
1446 break;
1447 /* UNIX time of coredump */
1448 case 't': {
1449 struct timeval tv;
1450 do_gettimeofday(&tv);
1451 rc = snprintf(out_ptr, out_end - out_ptr,
1452 "%lu", tv.tv_sec);
1453 if (rc > out_end - out_ptr)
1454 goto out;
1455 out_ptr += rc;
1456 break;
1457 }
1458 /* hostname */
1459 case 'h':
1460 down_read(&uts_sem);
1461 rc = snprintf(out_ptr, out_end - out_ptr,
1462 "%s", utsname()->nodename);
1463 up_read(&uts_sem);
1464 if (rc > out_end - out_ptr)
1465 goto out;
1466 out_ptr += rc;
1467 break;
1468 /* executable */
1469 case 'e':
1470 rc = snprintf(out_ptr, out_end - out_ptr,
1471 "%s", current->comm);
1472 if (rc > out_end - out_ptr)
1473 goto out;
1474 out_ptr += rc;
1475 break;
1476 /* core limit size */
1477 case 'c':
1478 rc = snprintf(out_ptr, out_end - out_ptr,
1479 "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1480 if (rc > out_end - out_ptr)
1481 goto out;
1482 out_ptr += rc;
1483 break;
1484 default:
1485 break;
1486 }
1487 ++pat_ptr;
1488 }
1489 }
1490 /* Backward compatibility with core_uses_pid:
1491 *
1492 * If core_pattern does not include a %p (as is the default)
1493 * and core_uses_pid is set, then .%pid will be appended to
1494 * the filename. Do not do this for piped commands. */
1495 if (!ispipe && !pid_in_pattern
1496 && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1497 rc = snprintf(out_ptr, out_end - out_ptr,
1498 ".%d", task_tgid_vnr(current));
1499 if (rc > out_end - out_ptr)
1500 goto out;
1501 out_ptr += rc;
1502 }
1503out:
1504 *out_ptr = 0;
1505 return ispipe;
1506}
1507
1508static void zap_process(struct task_struct *start)
1509{
1510 struct task_struct *t;
1511
1512 start->signal->flags = SIGNAL_GROUP_EXIT;
1513 start->signal->group_stop_count = 0;
1514
1515 t = start;
1516 do {
1517 if (t != current && t->mm) {
1518 t->mm->core_waiters++;
1519 sigaddset(&t->pending.signal, SIGKILL);
1520 signal_wake_up(t, 1);
1521 }
1522 } while ((t = next_thread(t)) != start);
1523}
1524
1525static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1526 int exit_code)
1527{
1528 struct task_struct *g, *p;
1529 unsigned long flags;
1530 int err = -EAGAIN;
1531
1532 spin_lock_irq(&tsk->sighand->siglock);
1533 if (!signal_group_exit(tsk->signal)) {
1534 tsk->signal->group_exit_code = exit_code;
1535 zap_process(tsk);
1536 err = 0;
1537 }
1538 spin_unlock_irq(&tsk->sighand->siglock);
1539 if (err)
1540 return err;
1541
1542 if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1543 goto done;
1544
1545 rcu_read_lock();
1546 for_each_process(g) {
1547 if (g == tsk->group_leader)
1548 continue;
1549
1550 p = g;
1551 do {
1552 if (p->mm) {
1553 if (p->mm == mm) {
1554 /*
1555 * p->sighand can't disappear, but
1556 * may be changed by de_thread()
1557 */
1558 lock_task_sighand(p, &flags);
1559 zap_process(p);
1560 unlock_task_sighand(p, &flags);
1561 }
1562 break;
1563 }
1564 } while ((p = next_thread(p)) != g);
1565 }
1566 rcu_read_unlock();
1567done:
1568 return mm->core_waiters;
1569}
1570
1571static int coredump_wait(int exit_code)
1572{
1573 struct task_struct *tsk = current;
1574 struct mm_struct *mm = tsk->mm;
1575 struct completion startup_done;
1576 struct completion *vfork_done;
1577 int core_waiters;
1578
1579 init_completion(&mm->core_done);
1580 init_completion(&startup_done);
1581 mm->core_startup_done = &startup_done;
1582
1583 core_waiters = zap_threads(tsk, mm, exit_code);
1584 up_write(&mm->mmap_sem);
1585
1586 if (unlikely(core_waiters < 0))
1587 goto fail;
1588
1589 /*
1590 * Make sure nobody is waiting for us to release the VM,
1591 * otherwise we can deadlock when we wait on each other
1592 */
1593 vfork_done = tsk->vfork_done;
1594 if (vfork_done) {
1595 tsk->vfork_done = NULL;
1596 complete(vfork_done);
1597 }
1598
1599 if (core_waiters)
1600 wait_for_completion(&startup_done);
1601fail:
1602 BUG_ON(mm->core_waiters);
1603 return core_waiters;
1604}
1605
1606/*
1607 * set_dumpable converts traditional three-value dumpable to two flags and
1608 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1609 * these bits are not changed atomically. So get_dumpable can observe the
1610 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1611 * return either old dumpable or new one by paying attention to the order of
1612 * modifying the bits.
1613 *
1614 * dumpable | mm->flags (binary)
1615 * old new | initial interim final
1616 * ---------+-----------------------
1617 * 0 1 | 00 01 01
1618 * 0 2 | 00 10(*) 11
1619 * 1 0 | 01 00 00
1620 * 1 2 | 01 11 11
1621 * 2 0 | 11 10(*) 00
1622 * 2 1 | 11 11 01
1623 *
1624 * (*) get_dumpable regards interim value of 10 as 11.
1625 */
1626void set_dumpable(struct mm_struct *mm, int value)
1627{
1628 switch (value) {
1629 case 0:
1630 clear_bit(MMF_DUMPABLE, &mm->flags);
1631 smp_wmb();
1632 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1633 break;
1634 case 1:
1635 set_bit(MMF_DUMPABLE, &mm->flags);
1636 smp_wmb();
1637 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1638 break;
1639 case 2:
1640 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1641 smp_wmb();
1642 set_bit(MMF_DUMPABLE, &mm->flags);
1643 break;
1644 }
1645}
1646
1647int get_dumpable(struct mm_struct *mm)
1648{
1649 int ret;
1650
1651 ret = mm->flags & 0x3;
1652 return (ret >= 2) ? 2 : ret;
1653}
1654
1655int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1656{
1657 char corename[CORENAME_MAX_SIZE + 1];
1658 struct mm_struct *mm = current->mm;
1659 struct linux_binfmt * binfmt;
1660 struct inode * inode;
1661 struct file * file;
1662 int retval = 0;
1663 int fsuid = current->fsuid;
1664 int flag = 0;
1665 int ispipe = 0;
1666 unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1667 char **helper_argv = NULL;
1668 int helper_argc = 0;
1669 char *delimit;
1670
1671 audit_core_dumps(signr);
1672
1673 binfmt = current->binfmt;
1674 if (!binfmt || !binfmt->core_dump)
1675 goto fail;
1676 down_write(&mm->mmap_sem);
1677 /*
1678 * If another thread got here first, or we are not dumpable, bail out.
1679 */
1680 if (mm->core_waiters || !get_dumpable(mm)) {
1681 up_write(&mm->mmap_sem);
1682 goto fail;
1683 }
1684
1685 /*
1686 * We cannot trust fsuid as being the "true" uid of the
1687 * process nor do we know its entire history. We only know it
1688 * was tainted so we dump it as root in mode 2.
1689 */
1690 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */
1691 flag = O_EXCL; /* Stop rewrite attacks */
1692 current->fsuid = 0; /* Dump root private */
1693 }
1694
1695 retval = coredump_wait(exit_code);
1696 if (retval < 0)
1697 goto fail;
1698
1699 /*
1700 * Clear any false indication of pending signals that might
1701 * be seen by the filesystem code called to write the core file.
1702 */
1703 clear_thread_flag(TIF_SIGPENDING);
1704
1705 /*
1706 * lock_kernel() because format_corename() is controlled by sysctl, which
1707 * uses lock_kernel()
1708 */
1709 lock_kernel();
1710 ispipe = format_corename(corename, core_pattern, signr);
1711 unlock_kernel();
1712 /*
1713 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1714 * to a pipe. Since we're not writing directly to the filesystem
1715 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1716 * created unless the pipe reader choses to write out the core file
1717 * at which point file size limits and permissions will be imposed
1718 * as it does with any other process
1719 */
1720 if ((!ispipe) && (core_limit < binfmt->min_coredump))
1721 goto fail_unlock;
1722
1723 if (ispipe) {
1724 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1725 /* Terminate the string before the first option */
1726 delimit = strchr(corename, ' ');
1727 if (delimit)
1728 *delimit = '\0';
1729 delimit = strrchr(helper_argv[0], '/');
1730 if (delimit)
1731 delimit++;
1732 else
1733 delimit = helper_argv[0];
1734 if (!strcmp(delimit, current->comm)) {
1735 printk(KERN_NOTICE "Recursive core dump detected, "
1736 "aborting\n");
1737 goto fail_unlock;
1738 }
1739
1740 core_limit = RLIM_INFINITY;
1741
1742 /* SIGPIPE can happen, but it's just never processed */
1743 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1744 &file)) {
1745 printk(KERN_INFO "Core dump to %s pipe failed\n",
1746 corename);
1747 goto fail_unlock;
1748 }
1749 } else
1750 file = filp_open(corename,
1751 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1752 0600);
1753 if (IS_ERR(file))
1754 goto fail_unlock;
1755 inode = file->f_path.dentry->d_inode;
1756 if (inode->i_nlink > 1)
1757 goto close_fail; /* multiple links - don't dump */
1758 if (!ispipe && d_unhashed(file->f_path.dentry))
1759 goto close_fail;
1760
1761 /* AK: actually i see no reason to not allow this for named pipes etc.,
1762 but keep the previous behaviour for now. */
1763 if (!ispipe && !S_ISREG(inode->i_mode))
1764 goto close_fail;
1765 /*
1766 * Dont allow local users get cute and trick others to coredump
1767 * into their pre-created files:
1768 */
1769 if (inode->i_uid != current->fsuid)
1770 goto close_fail;
1771 if (!file->f_op)
1772 goto close_fail;
1773 if (!file->f_op->write)
1774 goto close_fail;
1775 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1776 goto close_fail;
1777
1778 retval = binfmt->core_dump(signr, regs, file, core_limit);
1779
1780 if (retval)
1781 current->signal->group_exit_code |= 0x80;
1782close_fail:
1783 filp_close(file, NULL);
1784fail_unlock:
1785 if (helper_argv)
1786 argv_free(helper_argv);
1787
1788 current->fsuid = fsuid;
1789 complete_all(&mm->core_done);
1790fail:
1791 return retval;
1792}